In this paper we have considered Wiesner's quantum money scheme in the generalised probabilistic theory framework.
We first defined the class of GPTs in which there is potential for unforgeable money, that is, those satisfying the \(\mathbf {WNC}\)  assumption.
We then demonstrate that under an assumption of Verification Sharpness, this is equivalent to the inability to broadcast arbitrary causal states — a general feature of non-classical GPTs, for example, those in [1]}.
